OK, in the 1911 Census for the Margaret Wilson (nee Downey) with children including Cecil, it states she was born Ballymena, whereas clairef says Larne.
There was a Margaret Downey born in Ballymena District, in 1884.Townland looks to be Clonkeen, Drummaul Parish. Her father was a Thomas.
If she was this Margaret rather than the Larne one, I'm not seeing a c1904 marriage to a John Wilson.